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Day 7 - Notes. Unit: Chemical Quantities. Determining the Molecular Formula from the Empirical Formula. After today, you will be able to…. Calculate the empirical formulas for various compounds given their percent makeup. Molecular Formula Determination from the Empirical Formula.
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Day 7 - Notes Unit: Chemical Quantities Determining the Molecular Formula from the Empirical Formula
After today, you will be able to… Calculate the empirical formulas for various compounds given their percent makeup
Molecular Formula Determination from the Empirical Formula To determine molecular formulas from the empirical formula follow these steps: • First determine the empirical formula • Use the formula: • Multiply the subscripts in the empirical formula by this whole number to get the molecular formula Molar mass of molecular formula Molar mass of empirical formula
1 mol C 12.01gC 6.16 70.4gC 8.70gH 17.3gN Example: What is the molecular formula for a compound that is 74.0% C, 8.70% H, and 17.3% N and has a molar mass of 243.39g? Empirical: C5H7N x = = 5 5C=12.01(5) = 60.05 1 mol H 1.01gH 8.61 7H=1.01(7) = 7.07 = x 1.23 1.23 1.23 = 7 1N=14.01(1) = +14.01 1 mol N 14.01gN 1.23 81.07 1 = x = = 3 x C5H7N C15H21N3 243.39 81.07
HOMEWORK: Time to Practice!Complete WS 7